Fuel rail pressure help

[AirFishAutomotive]

Having an issue with frp and didn't know if you had any ideas. Truck is an 08/studded w all ******s. And rebuilt motor

ran extremely well and then seemed like it fell on its face after about 2k miles , didn't have mid to top end power

After looking into rail pressure noticed it was only holding about 19k at wot on the biggest tune .

Switched hpfp (with one we had on the shelf, plug was a little messed up ) and while cab was up put a 72mm atmo on it.

Truck ran fine but frp seemed to still be the same. holding about 19-20k at wot.

The plug ended up coming back to bite us in the ass and put another new hpfp from ford in the truck along with frp sensor and harness, and rail pressure is still about the same at 19-20k mark, this is with a 2.28 pw tune. Put an ad2 4g on it and hpf stayed about the same. Switching To a hot street tune 2.0 pw the truck will hold 22k. We bumped the pressure on the ad2 from 10 psi to 16 psi and no change in rail pressure.

Truck has fresh ad filters in it, and we removed the topside filter and stand just to eliminate any kind of possible restriction.

Also during wot with the 72mm and a mishi intercooler the truck will run 1600 egt

Just seems odd that when the truck was first put together it seemed to have more power and then we went into switching these hpfp around with no change.

Stock nozzles and rails as well.

Any help would be greatly appreciate as it is driving me nuts

 

[AirFishAutomotive]

Also boost is around 52 psi at wot, fuel cooler is still on the truck instead of using factory cooler it has a mishi dual flow cooler.



Again the odd thing about all of this is the truck slowed down a good amount, that's why we started looking at hpf and learned the readings were low. Unfourtantly did not moniter pressure when the truck was first put together because it was literally perfect

 

[6.0 Tech]

Frp sensor, uvc harness all good? Jumper harness to the hpfp gasket good? Frp voltage koeo?

 

[AirFishAutomotive]

Fuel rail pressure sensor is brand new. Will check voltage key off today. At idle voltage is around 1.2 or 5100ish

 

[AirFishAutomotive]

KOEO everything is in spec voltage wise

Also frp desired mirrors actual during normal driving, it will just not hold during wot

Truck is getting 11+ psi @ shrader valve

 

[RescueF250]

Run it at a lower pulse and see what it does.

 

[6.4 Stroker]

Injectors very well could be returning too much fuel.
Seems to be common when they get a few miles.
I battled a very simular problem for awhile.
Had everything new from the lift pump forward and still wouldn't maintain rail psi.

 

[6.4f350]

Sounds like injector(s) are bleeding it off internally to the return.

 

[AirFishAutomotive]

Run it at a lower pulse and see what it does.

1.9 pw truck will hold 22k max
2.28 pw truck will hold 19-20k

These injectors have approx 80k on them.


To much on the return side would only show during wot?


Going to run a dye test this am to just make sure there are no leaks

 

[AirFishAutomotive]

Injectors very well could be returning too much fuel.
Seems to be common when they get a few miles.
I battled a very simular problem for awhile.
Had everything new from the lift pump forward and still wouldn't maintain rail psi.

So new injectors solved your issue?

 

[6.4 Stroker]

From my understanding the only way to find out is to have them tested.
Josh at RCD shared a good article about it awhile back.
Definitely a good idea to try the dye.
I never had found anything with mine, but hopefully you will.

 

[6.4 Stroker]

So new injectors solved your issue?

I was on a budget at the time so I found some low mile used, but it did take care of it yes.

 

[AirFishAutomotive]

Passed dye test, put 8 new injectors and new uvc harness in the truck and no change.

 

[webb06]

Passed dye test, put 8 new injectors and new uvc harness in the truck and no change.

At WOT what is desired frp and actual frp? You said at idle they're the same right?


Sent from my iPhone using Tapatalk

 

[AirFishAutomotive]

Idle it will range now 48-53 for a split second or 2,normally will stay around the 5050/ 5100 mark desired 5071

Wot desired is 24.6 and actual is 19-20k

 

[78f100]

I had similar issue once, make absolutely sure you don't have a slight leak some where. Mine ended up being a fuel rail. Truck would not maintain full rp at wot. Had a newer pump and injectors, so i swapped injectors out (new lines also) with a set of known good ones, same issue. I ended up pulling the valve covers and ran the fuel pressure test on ids. When it commanded fp above 15000 i started getting a fuel mist off cyl 6 rail right behind where the line attaches. So i thought it was the line, put another new one on same thing. I swapped the rails, fixing the problem. I swear somehow that rail was cracked, they were ported rails so not sure if it happened during the porting process or what. It never really put enough fuel in the oil to tell either, it only seemed to leak under really high pressure. If you do it like that be very careful as I'm sure you know that much fp is dangerous. Hope you figure it out.

 

[6.4 Stroker]

That blows, honestly thought it would fix it.
Sounds your problem isn't a typical one.
If you try what 78f100 recommended, let us know what you find.

 

[AirFishAutomotive]

That blows, honestly thought it would fix it.
Sounds your problem isn't a typical one.
If you try what 78f100 recommended, let us know what you find.

going to try when we get some free time, backed up atm in the shop so can only mess with it in spurts

 

[78f100]

Did you ever figure anything out?

 

[AirFishAutomotive]

Did you ever figure anything out?

a lot of it seems to be in the tune and a possible false reading, switched to a ******* tune with a slightly higher pw 2.29 and it held 22-23k. After swapping injectors/hpfp/fuel tank/lines/fuel cooler there was no change. Ended up getting another pcm and reflashed it to stock and got completely new tunes essentially starting over on the truck, electronics wise. With the new tunes and pcm and back to our original tuner the truck will only show its holding 19k but with a desired 24k , the truck holds 19k with very little fluctuation on scan tool vs the 2k fluctuation it had before. Have not confirmed this frp on another scan tool or cts2 but the truck is a "monster" (used very loosely) for what is done to it after the pcm switch and reflash.


So basically I feel like it was something in the original pcm along with receiving a false reading, our pressure holds steady (only showing 19k) but the truck is much much quicker then it was previously.


Not sure if that helps or not but the loss of power all seems to be in connection to the original pcm that was in the truck, because after the switch and running an employees cummins in "mexico" this truck will now put multiple lengths on it over what it previously would do.


sorry did not update this has all happened since friday.